Touchpads seemingly are the de facto industry-standard pointing device built into portable computing devices (e.g., laptops, netbooks, notebooks, etc.). Typically, a touchpad (i.e., trackpad) has a small, flat, touch-sensitive surface area that senses the position of a user's finger (or fingers) on its surface to provide on-screen navigation, cursor movement, application control, and/or other user-interactive input to a computing device. Conventionally, touchpads work by sensing the changes in an electrical field using, for example, capacitance or conductance (i.e., resistance).
Capacitive touchpads (e.g., projected or surface capacitive) primarily detect location on the two-dimensional surface of the touchpad of the user's touch. This location may be called the “X/Y position” herein. Due to the nature of the technology, sensor designs, and environmental conditions, the “touch threshold” can vary quite widely.
FIG. 1 illustrates a conventional touchpad scenario 100, which shows a user's finger 102 hovering over a cross-section of a user-interactive portion 104 of a conventional touchpad. This portion 104 includes a touchsurface 106 and a conventional capacitive touch sensor 108. A region of varying capacitance (i.e., “circuit”) 110 lies between the finger 102 and the capacitive touch sensor 108. Typically, the finger 102 is determined to have “touched” the touchsurface 106 when the capacitance of the circuit 110 exceeds a given threshold, as measured by the sensor 108.
The capacitive sensor 108 is generally designed to detect the user touching the touchsurface 106, but, depending on the size, skin humidity, and physiological factors of a user's finger and/or environmental conditions, the point at which the touch is detected can vary widely as the capacitance circuit 110 varies. Indeed, a projected-capacitance touchpad may “detect” a touch before a user has actually touched the touchpad.
In general, a touchpad is often used much like a mouse of a computer. For example, a mouse typically has one or more buttons to indicate performance of a function (i.e., action) associated with a cursor position. Such functions are called cursor-position associative functions and examples of such include (but are not limited to): menu pull down and selection, icon selection and use, program execution, properties access, and the like. Most mouse users are familiar with single-click, double-click, and right-click, and the corresponding action expected based upon the cursor location on the screen.
Many conventional touchpads are equipped with similar buttons to accomplish the same cursor-position associative functions. Instead of, or in addition to, buttons, some touchpads allow the user to indicate the performance of cursor-position associative functions based upon an action or gesture performed on the touchpad itself. For example, a user may indicate a “single-click” once the cursor has arrived at its desired spot by quickly tapping the touchpad. A “double-click” may be accomplished likewise with a double tap. Alternatively, a single or multi-finger gesture may accomplish a similar “mouse click.”
All of the existing capacitive touchpad approaches offer an awkward or non-intuitive action for a user to select the performance of cursor-position associative functions. Examples of such awkward or non-intuitive actions include clicking a button with a different hand than the one touching the touchpad, clicking a button with a different finger on the same hand as the touchpad, tapping the touchpad, and touching the touchpad with a defined single- or multi-finger gesture.